U.S. patent number 7,037,594 [Application Number 10/190,596] was granted by the patent office on 2006-05-02 for electromagnetic wave shielding member and process for producing the same.
This patent grant is currently assigned to Dai Nippon Printing Co., Ltd.. Invention is credited to Fumihiro Arakawa, Hiroshi Kojima.
United States Patent |
7,037,594 |
Kojima , et al. |
May 2, 2006 |
Electromagnetic wave shielding member and process for producing the
same
Abstract
There is provided an electromagnetic wave shielding member which
has see-through properties and electromagnetic wave shielding
properties, is free from a change in color of an adhesive at the
time of the formation of a mesh by etching, is improved in
etchability, and can withstand etching at the time of the formation
of the mesh. The electromagnetic wave shielding member according to
the present invention comprises: a transparent film substrate; and
a mesh consisting of a metal foil provided on the surface of the
substrate through an adhesive, the adhesive comprising a
styrene-maleic acid copolymer-modified polyesterpolyurethane and an
aliphatic polyisocyanate.
Inventors: |
Kojima; Hiroshi (Shinjuku-ku,
JP), Arakawa; Fumihiro (Shinjuku-ku, JP) |
Assignee: |
Dai Nippon Printing Co., Ltd.
(Tokyo, JP)
|
Family
ID: |
26618366 |
Appl.
No.: |
10/190,596 |
Filed: |
July 9, 2002 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20030094296 A1 |
May 22, 2003 |
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Foreign Application Priority Data
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Jul 9, 2001 [JP] |
|
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2001-207930 |
Sep 13, 2001 [JP] |
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2001-277410 |
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Current U.S.
Class: |
428/601; 216/56;
428/458; 428/624; 428/626; 428/674; 428/607; 428/457; 216/100;
156/330.9; 156/331.7; 156/326; 174/389 |
Current CPC
Class: |
H05K
9/0096 (20130101); Y10T 428/31678 (20150401); Y10T
428/12556 (20150115); Y10T 428/12569 (20150115); Y10T
428/12396 (20150115); Y10T 428/12438 (20150115); Y10T
428/12903 (20150115); Y10T 428/31681 (20150401) |
Current International
Class: |
B32B
15/08 (20060101); B32B 15/09 (20060101); B32B
15/20 (20060101); C09J 175/00 (20060101); H05K
9/00 (20060101) |
Field of
Search: |
;428/606,607,609,600,601,624,626,674,335,336,457,458,461
;174/35R,35MS ;156/326,325,330.9,331.4,331.7,332,331.9
;216/83,100,105,41,56 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Lavilla; Michael E.
Attorney, Agent or Firm: Oliff & Berridge PLC
Claims
What is claimed is:
1. An electromagnetic wave shielding member comprising: a
transparent film substrate; and a thin metal film mesh provided on
a surface of the substrate through an adhesive, said adhesive
comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate.
2. The electromagnetic wave shielding member according to claim 1,
wherein the film substrate is polyethylene terephthalate and the
thin metal film mesh has a thickness of 5 to 20 .mu.m.
3. The electromagnetic wave shielding member according to claim 1,
wherein the thin metal film mesh is a copper foil and the thin
metal film mesh has been roughened by cathodically
electrodepositing copper bosses on at least one side of the copper
foil, and at least one side of the copper foil has been
chromated.
4. The electromagnetic wave shielding member according to claim 3,
wherein the surface, on which the copper bosses have been
cathodically electrodeposited, has been bonded to the film
substrate.
5. A process for producing the electromagnetic wave shielding
member of claim 1, comprising the steps of: laminating a thin metal
film on the surface of the transparent film substrate with the aid
of the adhesive; and etching the laminated thin metal film to form
the mesh, said adhesive comprising a styrene-maleic acid said
adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate.
6. The process according to claim 5, wherein ferric chloride is
used in the etching treatment.
7. An electromagnetic wave shielding member comprising: a
transparent film substrate; and a thin metal film mesh provided on
a surface of the substrate through an adhesive, said adhesive
comprising: (a) a polyesterpolyurethanepolyol produced by reacting
a polyesterpolyol with a polyisocyanate, (b) a carboxyl-containing
polyesterpolyol produced by reacting a polyesterpolyol with an
aromatic polycarboxylic anhydride, and (c) a mixture of a
trimethylolpropane adduct of isophorone diisocyanate with a
trimethylolpropane adduct of xylylene diisocyanate.
8. The electromagnetic wave shielding member according to claim 7,
wherein said polyesterpolyol comprises: (a) an ester of isophthalic
acid with ethylene glycol and neopentyl glycol, (b) an ester of
isophthalic acid with diethylene glycol, (c) an ester of
isophthalic acid with ethylene glycol, neopentyl glycol, and
2,5-hexanediol, or (d) a mixture of said esters (a) to (c).
9. The electromagnetic wave shielding member according to claim 7,
wherein the film substrate is polyethylene terephthalate and the
thin metal film mesh has a thickness of 5 to 20 .mu.m.
10. The electromagnetic wave shielding member according to claim 7,
wherein the thin metal film mesh is a copper foil and the thin
metal film mesh has been roughened by cathodically
electrodepositing copper bosses on at least one side of the copper
foil, and at least one side of the copper foil has been
chromated.
11. A process for producing the electromagnetic wave shielding
member of claim 7, comprising the steps of: laminating a thin metal
film on the surface of the transparent film substrate with the aid
of the adhesive; and etching the laminated thin metal film to form
the mesh, said adhesive comprising: (a) a
polyesterpolyurethanepolyol produced by reacting a polyesterpolyol
with a polyisocyanate, (b) a carboxyl-containing polyesterpolyol
produced by reacting a polyesterpolyol with an aromatic
polycarboxylic anhydride, and (c) a mixture of a trimethylolpropane
adduct of isophorone diisocyanate with a trimethylolpropane adduct
of xylylene diisocyanate.
12. The process according to claim 11, wherein ferric chloride is
used in the etching treatment.
13. An electromagnetic wave shielding member comprising: a
transparent film substrate; and a thin metal film mesh provided on
a surface of the substrate through an adhesive, said adhesive
comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, said
adhesive containing an absorber which can absorb specific
wavelengths, in at least one of the visible light wavelength region
and the near-infrared wavelength region.
14. The electromagnetic wave shielding member according to claim
13, wherein flattening a layer for flattening a concave-convex
surface of the mesh is further provided on the thin metal film
mesh.
15. The electromagnetic wave shielding member according to claim
14, wherein the flattening layer is provided on the thin metal film
mesh through a pressure-sensitive adhesive, and at least one of the
flattening layer and the pressure-sensitive adhesive also contains
an absorber which can absorb specific wavelengths in at least one
of the visible light wavelength region and the near-infrared
wavelength region.
16. The electromagnetic wave shielding member according to claim
14, wherein the flattening layer also contains an absorber which
can absorb specific wavelengths in at least one of the visible
light wavelength region and the near-infrared wavelength
region.
17. An electromagnetic wave shielding member comprising: a
transparent film substrate; and a thin metal film mesh provided on
a surface of the substrate through an adhesive, said adhesive
comprising (a) a polyesterpolyurethanepolyol produced by reacting a
polyesterpolyol with a polyisocyanate, (b) a carboxyl-containing
polyesterpolyol produced by reacting a polyesterpolyol with an
aromatic polycarboxylic anhydride, and (c) a mixture of a
trimethylolpropane adduct of isophorone diisocyanate with a
trimethylolpropane adduct of xylylene diisocyanate, said adhesive
containing an absorber which can absorb specific wavelengths, in at
least one of the visible light wavelength region and the
near-infrared wavelength region.
18. The electromagnetic wave shielding member according to claim
17, wherein a flattening layer for flattening a concave-convex
surface of the mesh is further provided on the thin metal film
mesh.
19. The electromagnetic wave shielding member according to claim
18, wherein the flattening layer is provided on the thin metal film
mesh through a pressure-sensitive adhesive, and at least one of the
flattening layer and the pressure-sensitive adhesive also contains
an absorber which can absorb specific wavelengths in at least one
of the visible light wavelength region and the near-infrared
wavelength region.
20. The electromagnetic wave shielding member according to claim
18, wherein the flattening layer also contains an absorber which
can absorb specific wavelengths in at least one of the visible
light wavelength region and the near-infrared wavelength region.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic wave shielding
member using a mesh consisting of a thin metal film (also known as
"metal foil") and a process for producing the same.
More specifically, the present invention relates to an
electromagnetic wave shielding member using a mesh consisting of a
thin metal film, for shielding electromagnetic waves generated from
electromagnetic wave sources, such as electronic tubes of displays,
which electromagnetic wave shielding member has see-through
properties and electromagnetic wave shielding properties and, at
the same time, is free from a change in color of an adhesive upon
etching at the time of the formation of the mesh, is improved in
etchability, and can withstand etching at the time of the formation
of the mesh. The present invention also relates to an
electromagnetic wave shielding member which can improve contrast
and can realize good visibility. Further, the present invention
relates to an electromagnetic wave shielding member which,
according to need, can cut or absorb near-infrared radiation
(light) generated from the inside of displays and can absorb
specific wavelengths, i.e., the wavelengths of external
light-derived visible light and/or near-infrared radiation (light)
to improve contrast and can realize good visibility.
2. Prior Art
From the viewpoint of a harmful effect of electromagnetic waves on
the human body, lowering the emission intensity of electromagnetic
waves to values satisfying specifications has hitherto been
required of electronic devices, which generate electromagnetic
waves and, in use, are accessed directly by a person, for example,
electronic tubes of displays, for example, plasma displays.
Further, in plasma display panels (hereinafter referred to also as
"PDPs"), since plasma discharge is utilized for light emission,
unnecessary electromagnetic waves in the frequency band range of 30
to 130 MHz are leaked outside the plasma display panels. For this
reason, minimizing electromagnetic waves is required from the
viewpoint of avoiding a harmful effect on other equipment (for
example, information processing devices).
To cope with these demands, electromagnetic wave shields, wherein
the outer periphery of electronic devices or the like, which
generate electromagnetic waves, is covered with a suitable
conductive member, are generally adopted for removing or
attenuating electromagnetic waves that flow out from electronic
devices, which generate electromagnetic waves, to the outside of
the devices.
In display panels such as PDPs, it is common practice to provide an
electromagnetic wave shielding plate having good see-through
properties in front of a display.
The fundamental structure per se of electromagnetic wave shielding
plates is relatively simple, and examples of conventional
electromagnetic wave shielding plates include: an electromagnetic
wave shielding plate wherein a thin transparent conductive film,
such as a thin indium-tin oxide film (hereinafter referred to also
as "ITO film"), has been formed by vapor deposition on the surface
of a transparent glass or plastic substrate, sputtering or the
like; an electromagnetic wave shielding plate wherein, for example,
a suitable metallic screen, such as a wire mesh, has been applied
to the surface of a transparent glass or plastic substrate; and an
electromagnetic wave shielding plate wherein a fine mesh consisting
of a thin metal film has been provided on the surface of a
transparent glass or plastic substrate by forming a thin metal film
on the whole surface of the substrate, for example, by electroless
plating or vapor deposition and treating the thin metal film by
photolithography or the like.
The electromagnetic wave shielding plate comprising an ITO film
provided on a transparent substrate has excellent transparency and
generally has a light transmittance of about 90%. Further, since an
even film can be formed on the whole surface of the substrate, when
the electromagnetic wave shielding plate is used in displays or the
like, there is no fear of causing moire or the like attributable to
the electromagnetic wave shielding plate.
In the electromagnetic wave shielding plate comprising an ITO film
provided on a transparent substrate, however, since a vapor
deposition or sputtering technique is used for the formation of the
ITO film, the production apparatus used is expensive. Further, the
productivity is generally poor. This poses a problem that the price
of the electromagnetic wave shielding plate per se as a product is
high.
Further, the electromagnetic wave shielding plate comprising an ITO
film provided on a transparent substrate has at least one order
inferior electrical conductivity as compared with the
electromagnetic wave shielding plate provided with a mesh
consisting of a thin metal film. Therefore, this electromagnetic
wave shielding plate is effective for objects which emit relatively
weak electromagnetic waves, but on the other hand, when used in
objects which emit strong electromagnetic waves, the shielding
function is unsatisfactory posing a problem that electromagnetic
waves are leaked and, in some cases, the specifications cannot be
satisfied.
In the electromagnetic wave shielding plate comprising an ITO film
provided on a transparent substrate, increasing the thickness of
the ITO film can improve the electrical conductivity to some
extent. In this case, however, disadvantageously, the transparency
is remarkably deteriorated. In addition, a further increased
thickness incurs a further increased product cost.
The electromagnetic wave shielding plate comprising a metallic
screen applied onto the surface of a transparent glass or plastic
substrate or the application of a suitable metallic screen, such as
a wire mesh, directly onto the surface of a display is simple and
is low in cost. This, however, suffers from a serious drawback
that, since the light transmittance of a metallic screen having an
effective mesh size (100 to 200 mesh) is not more than 50%, the
display is very dark.
In the case of the electromagnetic wave shielding plate comprising
a mesh consisting of a thin metal film provided on the surface of a
transparent glass or plastic substrate, since the external form is
shaped by etching according to photolithography, a fine, high open
area ratio (high light transmittance) mesh can be prepared.
Further, since the mesh consists of a thin metal film, the
electrical conductivity is much higher than that of the ITO film or
the like. This offers an advantage that strong emitted
electromagnetic waves can be shielded.
This electromagnetic wave shielding plate, however, cannot absorb
the reflection of external light from the display panel and has
poor visibility and, in addition, suffers from an unavoidable
problem that the production process is troublesome and complicate
and the productivity is low resulting in high production cost.
Thus, the electromagnetic wave shielding plates have respective
advantages and disadvantages, and, in use, a suitable
electromagnetic wave shielding plate is selected according to
applications. Among the above electromagnetic wave shielding
plates, the electromagnetic wave shielding plate comprising a mesh
consisting of a thin metal film provided on the surface of a
transparent glass or plastic substrate has good electromagnetic
wave shielding properties and light transmission properties and has
recently become used for electromagnetic wave shielding purposes in
such a manner that the electromagnetic wave shielding plate is
placed in front of display panels such as PDPs.
In the conventional electromagnetic wave shielding plates and
displays, a feature, which cuts off or absorbs near-infrared
radiation (light) emitted from the inside of the display and can
absorb specific wavelengths, i.e., the wavelengths of visible light
emitted from the inside of the display or derived from external
light for improving the contrast, is stacked by a separate step,
for preventing malfunction of other equipment. Therefore,
disadvantageously, the process is troublesome, the productivity is
poor, and the thickness is large.
An electromagnetic wave shielding member comprising a mesh
consisting of a thin metal film provided on the surface of a
transparent glass or plastic substrate is shown in FIG. 4. This
electromagnetic wave shielding member will be briefly
described.
FIG. 4A is a plan view showing an electromagnetic wave shielding
member, FIG. 4B a cross-sectional view taken on line A1 A2 of FIG.
4A, and FIG. 4C an enlarged view of a part of a mesh portion.
In FIGS. 4A and 4C, direction X and direction Y are indicated for
the clarification of the positional relationship and mesh
shape.
The electromagnetic wave shielding member shown in FIGS. 4A to 4C
is an electromagnetic wave shielding member for an electromagnetic
wave shielding plate which, in use, is placed in front of displays
such as PDPs. In this electromagnetic wave shielding member, a
grounding frame portion and a mesh portion are provided on one side
of a transparent substrate. The grounding frame portion 415 is
formed of the same thin metal film as the mesh portion and is
provided around the periphery of the mesh portion 410 so as to
surround the screen region of the display in using the
electromagnetic wave shielding plate in such a manner that the
electromagnetic wave shielding plate is placed in front of a
display.
As shown in FIG. 4C (a partially enlarged view of the mesh portion
410), the mesh portion 410 comprises a group of a plurality of
lines 470 provided parallel to each other at a predetermined pitch
Px in direction Y and a group of a plurality of lines 450 provided
parallel to each other at a predetermined pitch Py in direction X.
In this connection, it should be noted that the shape of the mesh
is not limited to that shown in FIG. 4.
FIG. 5A shows an example of the case where an electromagnetic wave
shielding plate 500 using the electromagnetic wave shielding member
shown in FIG. 4 is used in such a state that the electromagnetic
wave shielding plate 500 is placed in front of PDP, and FIG. 5B an
enlarged cross-sectional view of an electromagnetic wave shielding
region (corresponding to portion B0) shown in FIG. 5A.
As shown in FIG. 5B, the electromagnetic wave shielding region
(corresponding to portion B0) in the electromagnetic wave shielding
plate 500 comprises, provided on the viewer side of a transparent
glass substrate 510, an NIR layer (a near-infrared absorption
layer) 530, an electromagnetic wave shielding member 400 shown in
FIG. 4, and a first AR layer (an antireflection layer) film 540 in
that order as viewed from the transparent glass substrate and, on
the PDP 570 side of the transparent glass substrate 510, a second
AR layer (an antireflection layer) film 520.
In FIG. 5, numeral 500 designates a front plate for display,
numeral 400 an electromagnetic wave shielding member, numeral 410 a
mesh portion, numeral 430 a transparent substrate, numeral 510 a
glass substrate, numeral 520 a second AR layer film, numeral 521 a
film, numeral 523 a hardcoat, numeral 525 an AR layer (an
antireflection layer), numeral 527 an antifouling layer, numeral
530 an NIR layer (an near-infrared absorption layer), numeral 540 a
first AR layer film, numeral 541 a film, numeral 543 a hardcoat,
numeral 545 an AR layer (an antireflection layer), numeral 547 an
antifouling layer, numerals 551, 553, and 555 each an adhesive
layer, numeral 570 PDP (a plasma display), numeral 571 an
attachment boss, numeral 573 a screw, numeral 572 a pedestal,
numeral 574 a mounting bracket, numeral 575 the front part of a
housing, numeral 576 the rear part of a housing, and numeral 577 a
housing. The position of the NIR layer (near-infrared absorption
layer) and the position of the electromagnetic wave shielding
member are not particularly limited to those shown in FIG. 5B.
Further, if necessary, a colored layer for color regulation may be
provided.
The use of an adhesive comprising an ethylene-vinyl acetate
copolymer has been proposed as a method for bonding an
electromagnetic wave shielding member to a transparent substrate
(Japanese Patent Laid-Open No. 307988/1999). In particular, it is
known that high adhesive strength and transparency are required of
the adhesive for electromagnetic wave shielding members for
displays. Since, however, the adhesive is not resistant to etching
at the time of the formation of a mesh, the color of the adhesive
is disadvantageously changed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an
electromagnetic wave shielding member for an electromagnetic wave
shielding plate, as shown in FIGS. 4A to 4C, comprising a mesh
consisting of a thin metal film provided on a transparent substrate
through an adhesive, which electromagnetic wave shielding member
has see-through properties and electromagnetic wave shielding
properties and, at the same time, is free from a change in color of
an adhesive upon etching at the time of the formation of the mesh,
is improved in etchability, and can withstand etching for the
formation of the mesh. It is another object of the present
invention to provide an electromagnetic wave shielding member
having excellent visibility. It is a further object of the present
invention to provide an electromagnetic wave shielding member
which, in a construction comprising a minimized number of layers
according to need, can cut off or absorb near-infrared radiation
(light) emitted from the inside of the display and can absorb
specific wavelengths, i.e., the wavelengths of visible light
emitted from the inside of the display or derived from external
light, for preventing the malfunction of other equipment, or for
improving the contrast of images or the like on the screen of the
display and for imparting good visibility.
According to one aspect of the present invention, there is provided
a first electromagnetic wave shielding member comprising: a
transparent film substrate; and a mesh consisting of a metal foil
provided on the surface of the substrate through an adhesive, said
adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate.
According to another aspect of the present invention, there is
provided a second electromagnetic wave shielding member comprising:
a transparent film substrate; and a mesh consisting of a metal foil
provided on the surface of the substrate through an adhesive, said
adhesive comprising (a) a polyesterpolyurethanepolyol produced by
reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate. The use
of this adhesive can provide an electromagnetic wave shielding
member which is excellent in etchability.
In a preferred embodiment of the second electromagnetic wave
shielding member according to the present invention, the
polyesterpolyol comprises (a) an ester of isophthalic acid with
ethylene glycol and neopentyl glycol, (b) an ester of isophthalic
acid with diethylene glycol, (c) an ester of isophthalic acid with
ethylene glycol, neopentyl glycol, and 2,5-hexanediol, or (d) a
mixture of said esters (a) to (c).
According to the present invention, there is provided a process for
producing an electromagnetic wave shielding member, comprising the
steps of: laminating a metal foil on the surface of a transparent
film substrate with the aid of an adhesive; and etching the
laminated metal foil to form a mesh, said adhesive comprising a
styrene-maleic acid copolymer-modified polyesterpolyurethane and an
aliphatic polyisocyanate.
In another embodiment of the process for producing an
electromagnetic wave shielding member according to the present
invention, the adhesive comprises (a) a polyesterpolyurethanepolyol
produced by reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate.
The lamination of a metal foil on a transparent film substrate
followed by etching of the metal foil in the laminate member to
form a mesh can provide an electromagnetic wave shielding member
having good quality.
According to the present invention, there is provided a third
electromagnetic wave shielding member comprising: a transparent
film substrate; and a mesh consisting of a thin metal film on the
surface of the substrate through an adhesive, said adhesive
comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, said
adhesive containing an absorber which can absorb specific
wavelengths, i.e., the wavelengths of visible light and/or
near-infrared.
According to the present invention, there is provided a fourth
electromagnetic wave shielding member comprising: a transparent
film substrate; and a mesh consisting of a thin metal film provided
on the surface of the substrate through an adhesive, said adhesive
comprising (a) a polyesterpolyurethanepolyol produced by reacting a
polyesterpolyol with a polyisocyanate, (b) a carboxyl-containing
polyesterpolyol produced by reacting a polyesterpolyol with an
aromatic polycarboxylic anhydride, and (c) a mixture of a
trimethylolpropane adduct of isophorone diisocyanate with a
trimethylolpropane adduct of xylylene diisocyanate, said adhesive
containing an absorber which can absorb specific wavelengths, i.e.,
the wavelengths of visible light and/or near-infrared.
In a preferred embodiment of the third or fourth electromagnetic
wave shielding member according to the present invention, a layer
for flattening the concave-convex surface of the mesh is further
provided on the mesh consisting of the thin metal film, and at
least one of the flattening layer and the adhesive contains an
absorber which can absorb specific wavelengths, i.e., the
wavelengths of visible light and/or near-infrared (see FIGS. 7 to
9).
In a further preferred embodiment, the flattening layer is provided
on the mesh through a pressure-sensitive adhesive, and at least one
of the flattening layer, the adhesive, and the pressure-sensitive
adhesive contains an absorber which can absorb specific
wavelengths, i.e., the wavelengths of visible light and/or
near-infrared (see FIGS. 7 to 9).
According to the present invention, there is provided a process for
producing an electromagnetic wave shielding member for an
electromagnetic wave shielding plate adapted for use in such a
manner that the electromagnetic wave shielding plate is placed in
front of a display, or alternatively may be applied directly to the
display, said electromagnetic wave shielding member having
electromagnetic wave shielding properties and see-through
properties and comprising a transparent film substrate and a mesh
consisting of a thin metal film at least one side of which has been
blackened by chromating or the like, said mesh being laminated on
one side of the substrate through an adhesive comprising a
styrene-maleic acid copolymer-modified polyesterpolyurethane and an
aliphatic polyisocyanate, or an adhesive comprising (a) a
polyesterpolyurethanepolyol produced by reacting a polyesterpolyol
with a polyisocyanate, (b) a carboxyl-containing polyesterpolyol
produced by reacting a polyesterpolyol with an aromatic
polycarboxylic anhydride, and (c) a mixture of a trimethylolpropane
adduct of isophorone diisocyanate with a trimethylolpropane adduct
of xylylene diisocyanate, said process comprising the steps of: (1)
a laminate member formation treatment wherein a continuous metal
foil strip and a continuous film substrate strip are laminated on
top of each other through the above adhesive to form a continuous
laminate member strip; (2) masking treatment wherein, while
carrying the laminate member in a continuous or intermittent
manner, an etching-resistant resist mask, for etching the metal
foil in the laminate member to form a mesh or the like, is
successively formed in a continuous or intermittent manner along
the longitudinal direction of the metal foil so as to cover the
metal foil on its surface remote from the film substrate; and (3)
etching treatment wherein the metal foil in its portions exposed
from openings of the resist mask is etched to form a mesh or the
like consisting of a thin metal film.
Before the lamination, both sides or one side of a copper foil or a
metal foil consisting of an iron material are blackened by chromate
treatment. Before the chromate treatment, copper bosses may be
adhered to the copper foil.
When both sides or one side of the copper foil or the metal foil
consisting of an iron material are not previously blackened by
chromate treatment, after the etching in the step (3), the resist
pattern is separated and removed and, if necessary, washing
treatment is carried out, followed by blackening of the exposed
surface of the mesh consisting of the thin metal film by chromate
treatment or the like.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a production process flow diagram showing an embodiment
of a production process of an electromagnetic wave shielding member
according to the present invention;
FIGS. 2A to 2G are partially sectional views illustrating masking
treatment, etching treatment, and laminating treatment for
laminating a silicone separator (a silicone-treated, easily
separable PET film);
FIG. 3A is a diagram showing a positional relationship between a
laminate member and a mesh portion and a grounding frame portion of
an electromagnetic wave shielding member to be formed;
FIG. 3B is a diagram showing a mesh portion and a grounding frame
portion;
FIG. 3C is a conceptual cross-sectional view showing the layer
construction of an electromagnetic wave shielding member;
FIG. 3D is a conceptual cross-sectional view showing the layer
construction of an electromagnetic wave shielding member;
FIG. 4A is a plan view of an electromagnetic wave shielding
member;
FIG. 4B is a cross-sectional view taken on line A1-A2 of FIG.
4A;
FIG. 4C is an enlarged view of a part of a mesh portion;
FIG. 5A is an embodiment of the use of an electromagnetic wave
shielding plate using the electromagnetic wave shielding member
shown in FIG. 4 wherein the electromagnetic wave shielding plate is
placed in front of PDP;
FIG. 5B is an enlarged cross-sectional view showing an
electromagnetic wave shielding region (corresponding to portion B0)
shown in FIG. 5A; FIG. 6A is a cross-sectional view showing an
embodiment of the layer construction of a metal foil 120 shown in
FIG. 2;
FIG. 6B is a cross-sectional view showing another embodiment of the
layer construction of the metal foil 120 shown in FIG. 2;
FIG. 7 is a cross-sectional view showing an embodiment of the layer
construction of the electromagnetic wave shielding member according
to the present invention;
FIG. 8 is a cross-sectional view showing another embodiment of the
layer construction of the electromagnetic wave shielding member
according to the present invention;
FIG. 9 is a typical cross-sectional view showing an embodiment of a
display onto which the electromagnetic wave shielding member
according to the present invention has been laminated;
FIG. 10 is a perspective view showing an embodiment of the layer
construction of the electromagnetic wave shielding member according
to the present invention (Example 1);
FIG. 11 is a cross-sectional view showing an embodiment of the
layer construction of a vertical section obtained by cutting an
electromagnetic wave shielding member 4000 shown in FIG. 10 in its
plane parallel to a mesh of a copper foil 1000 (Example 1); and
FIG. 12 is a typical cross-sectional view showing the state of a
copper foil 1000, before etching, with copper bosses 1300 deposited
thereon, constituting the electromagnetic wave shielding member
4000 shown in FIG. 11.
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with
reference to the accompanying drawings.
FIG. 1 is a production process flow diagram showing an embodiment
of a production process of an electromagnetic wave shielding member
according to the present invention, FIG. 2 a partially sectional
view illustrating masking treatment, etching treatment, and
laminating treatment for laminating a silicone separator (a
silicone-treated, easily separable PET film), FIG. 3A a diagram
showing a positional relationship between a laminate member and a
mesh portion and a grounding frame portion of an electromagnetic
wave shielding member to be formed, FIG. 3B a diagram showing a
mesh portion and a grounding frame portion, and FIGS. 3C and 3D
cross-sectional views showing the layer construction of an
electromagnetic wave shielding member. FIGS. 2A to 2G and FIGS. 3C
and 3D are cross-sectional views of position P1 P2 shown in FIG.
3B.
In FIGS. 1, 2, and 3, numeral 110 designates a film substrate,
numeral 120 a metal foil, numeral 120A a mesh portion, numeral 120B
a grounding frame portion, numeral 120C a treated portion, numeral
130 an adhesive layer, numeral 135 a pressure-sensitive adhesive
layer, numeral 140 a silicone separator (a protective film),
numeral 150 an NIR layer film, numeral 151 a film, numeral 152 an
NIR layer, numeral 160 an AR layer film, numeral 161 a film,
numeral 162 a hardcoat, numeral 163 an antireflection layer,
numeral 164 an antifouling layer, numerals 170 and 175 each an
adhesive layer, and numeral 190 a laminate member. In FIG. 1, S110
to S220 represent treatment steps.
FIGS. 6A and 6B are cross-sectional views showing two embodiments
of the layer construction of a metal foil 120 shown in FIG. 2.
Specifically, FIG. 6A is a cross-sectional view showing a metal
foil 120 wherein a chromate layer (a blackened layer) 122 is
provided on one side of a metal layer 121, and FIG. 6B a
cross-sectional view showing a metal foil 120 wherein a chromate
layer (a blackened layer) 122 is provided on both sides of a metal
layer 121.
At the outset, a first embodiment of the production process of an
electromagnetic wave shielding member according to the present
invention will be described with reference to FIG. 1.
The production process according to this embodiment aims to mass
produce an electromagnetic wave shielding member, shown in FIGS. 5A
and 5B, for use in the preparation of an electromagnetic wave
shielding plate used in such a manner that the electromagnetic wave
shielding plate is placed in front of displays such as PDP. The
electromagnetic wave shielding member has electromagnetic wave
shielding properties and see-through properties and comprises a
transparent film substrate and, provided on one side of the
substrate, a mesh consisting of a thin metal film at least one side
of which has been blackened by chromate treatment, said mesh being
laminated on one side of the substrate. In this case, a 1 to 100
.mu.m-thick copper foil or an iron material (low carbon steel) is
used as a metal foil for the formation of the mesh consisting of a
thin metal foil.
At the outset, a continuous film substrate wound into a roll form
is provided (S110) and is brought to a stretched state without
loosening (S111), and a continuous (chromated) metal foil wound
into a roll form is provided (S120) and is brought to a stretched
state without loosening (S122). A continuous metal foil 120 strip
is laminated (S130) onto one side of the continuous film substrate
110 strip through
an adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or
an adhesive comprising (a) a polyesterpolyurethanepolyol produced
by reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate,
to form a continuous laminate member 190 in a strip form wherein
the film substrate 110 and the metal foil 120 have been laminated
on top of each other (S140). The lamination can be carried out by
means of a laminate roll comprising a pair of rolls.
According to a more preferred embodiment, the transparent film
substrate is polyethylene terephthalate, and the metal foil has a
thickness of 5 to 20 .mu.m. When the thickness of the metal foil is
5 to 20 .mu.m, a mesh having a fine pattern can be prepared. When
the thickness of the metal foil is not more than 5 .mu.m, the
formation of the fine pattern becomes easy. In this case, however,
the electric resistance value of the metal is increased, and the
electromagnetic wave shielding effect is deteriorated. On the other
hand, when the thickness is not less than 20 .mu.m, it is difficult
to form the mesh having a fine pattern. Further, in this case,
since the open area ratio is substantially lowered, the light
transmittance is lowered and, in addition, the angle of view is
narrowed. That is, when the thickness of the metal foil is 5 to 20
.mu.m, an electromagnetic wave shielding member having excellent
visibility can be provided.
In the electromagnetic wave shielding member according to the
present invention, the mesh consisting of a thin metal film is not
always required to be blackened by chromate treatment. However, the
use of a mesh consisting of a thin metal film, at least one side of
which has been blackened by chromate treatment, is preferred.
In the electromagnetic wave shielding member according to the
present invention, preferably, the metal foil is a copper foil, at
least one side of the copper foil has been roughened by
cathodically electrodepositing copper bosses, and at least one side
of the metal foil has been chromated. This can provide an
electromagnetic wave shielding member having excellent visibility
(see FIGS. 11 and 12). When the metal foil is a copper foil, copper
bosses can be cathodically electrodeposited. Here the purpose and
method of the deposition of copper bosses by cathodic
electrodeposition will be described in detail. In order to improve
the visibility, preferably, the mesh pattern in its observer's side
is blackened and roughened. This can improve the contrast. The
blackening/roughening treatment is carried out by cathodically
electrolyzing the copper foil in an electrolysis solution
comprising sulfuric acid and copper sulfate to deposit cationic
copper particles. When the metal foil is a copper foil, copper
bosses can be cathodically electrodeposited. This can provide such
black that could not have hitherto been realized and can improve
the contrast of the display. Further, rust preventive chromate
treatment (hereinafter often referred to simply as "chromate
treatment") can improve handleability and can prevent a
deterioration in quality caused by rust.
More preferably, the metal foil on its surface with copper bosses
being cathodically electrodeposited thereon has been adhered to the
film substrate (see FIG. 11).
Further, in the electromagnetic wave shielding member according to
the present invention, a visible light absorption layer and/or a
near-infrared absorption layer may be provided. An antireflection
layer and/or an antiglare layer (1, 7) may also be provided in the
electromagnetic wave shielding member. A glass or acrylic
transparent substrate 2 may also be provided in the electromagnetic
wave shielding member (FIGS. 7 to 9). The electromagnetic wave
shielding member may be provided directly on the surface of a
display 15 (FIG. 9).
According to a preferred embodiment, in the electromagnetic wave
shielding member, a mesh consisting of a thin metal film, at least
one side of which has been blackened, for example, by chromate
treatment or by a metal oxide or a metal sulfide, is provided on
the surface of a transparent film substrate through an adhesive
comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or an
adhesive comprising (a) a polyesterpolyurethanepolyol produced by
reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate. The
electromagnetic wave shielding member having the above construction
has a combination of electromagnetic wave shielding properties with
see-through properties. Further, chromate treatment for surface
blackening for absorbing external light can provide a blackened
layer which has high black density and high adhesion to a
metal.
More preferably, the black density of the chromated surface of the
mesh consisting of the thin metal film is not less than 0.6. In
this case, external light can be absorbed, and, thus, good
visibility can be realized. Here all the measurements of black
density in the present invention were carried out with GRETAG SPM
100-11 of COLOR CONTROL SYSTEM manufactured by KIMOTO under
conditions of observation field of view=10 degrees and observation
light source=D50. In this case, illumination type was set to
density standard ANSI T, and each sample was measured after white
calibration. The production process of an electromagnetic wave
shielding member according to the present invention will be
described mainly with reference to the case where the blackening
has been carried out by chromate treatment.
When the surface roughness of the metal foil is not more than 0.5
.mu.m in terms of ten-point mean roughness Rz specified in JIS B
0601, the external light is subjected to mirror reflection which
deteriorates visibility, even in the case where the surface has
been blackened. On the other hand, when the ten-point mean
roughness Rz specified in JIS B 0601 is not less than 10 .mu.m, it
is difficult to coat an adhesive, a resist or the like onto the
metal foil. The surface roughness of the (electrolytic) metal foil
can be achieved by regulating the surface roughness of the metallic
roll in the production of the material.
The metal constituting the metal foil is not particularly limited,
and examples thereof include copper, iron, nickel, and chromium.
Among them, copper is most preferred from the viewpoints of the
deposition of copper bosses by cathodic electrodeposition,
shielding properties of electromagnetic waves, suitability for
etching, and handleability.
The copper foil may be a rolled copper foil or an electrolytic
copper foil. The electrolytic copper foil is particularly preferred
because a thickness of not more than 10 .mu.m can be realized, the
thickness is even, and the adhesion to the chromate film is good.
Preferably, before the chromate treatment, copper bosses are
adhered to the copper foil.
When the metal foil is an iron material (low-carbon steel, Ni--Fe
alloy), an electromagnetic wave shielding member, which is
particularly excellent in electromagnetic wave shielding
properties, can be prepared.
The iron material is preferably substantially Ni-free low-carbon
steel, such as low-carbon rimmed steel or low-carbon aluminum
killed steel, from the viewpoint of etching treatment. However, the
iron material is not limited to these steels only.
When the metal foil is thick, the formation of a high-definition
pattern having a small line width is difficult due to side etching.
On the other hand, when the metal foil is thin, satisfactory
electromagnetic wave shielding effect cannot be attained. For this
reason, the thickness of the metal foil is preferably 1 to 100
.mu.m, particularly preferably 5 to 20 .mu.m.
According to the present invention, there is provided a process for
producing an electromagnetic wave shielding member for an
electromagnetic wave shielding plate adapted for use in such a
manner that the electromagnetic wave shielding plate is placed in
front of a display, or alternatively may be applied directly to the
display, said electromagnetic wave shielding member having
electromagnetic wave shielding properties and see-through
properties and comprising a transparent film substrate and a mesh
consisting of a thin metal film at least one side of which has been
blackened by chromate treatment or the like, said mesh being
laminated on one side of the substrate through an adhesive
comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or an
adhesive comprising (a) a polyesterpolyurethanepolyol produced by
reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate, said
process comprising the steps of: (1) a laminate member formation
treatment (hereinafter referred to also as "lamination treatment")
wherein a continuous metal foil strip and a continuous film
substrate strip are laminated on top of each other through the
above adhesive to form a continuous laminate member strip; (2)
masking treatment wherein, while carrying the laminate member in a
continuous or intermittent manner, an etching-resistant resist
mask, for etching the metal foil in the laminate member to form a
mesh or the like, is successively formed in a continuous or
intermittent manner along the longitudinal direction of the metal
foil so as to cover the metal foil on its surface remote from the
film substrate; and (3) etching treatment wherein the metal foil in
its portions exposed from openings of the resist mask is etched to
form a mesh or the like consisting of a thin metal film.
Before the lamination, both sides or one side of a copper foil or a
metal foil consisting of an iron material are blackened by chromate
treatment. Before the chromate treatment, copper bosses may be
adhered to the copper foil.
When both sides or one side of the copper foil or the metal foil
consisting of an iron material are not previously blackened by
chromate treatment, after the etching in the step (3), the resist
pattern is separated and removed and, if necessary, washing
treatment is carried out, followed by blackening of the exposed
surface of the mesh consisting of the thin metal film by chromate
treatment or the like.
In the step (3), after the etching treatment, if necessary,
lamination treatment is carried out wherein an adhesive layer or a
pressure-sensitive adhesive layer containing an absorber capable of
absorbing specific wavelengths, i.e., the wavelengths of visible
light and/or near-infrared is provided on the surface of the mesh
consisting of the thin metal film, and a silicone separator (a
silicone-treated, easily separable PET film) is laminated thereon.
Further, the laminate member formation treatment in the step (1) is
lamination treatment wherein a continuous metal foil strip is
laminated onto the surface of a continuous film substrate strip
through the above adhesive to form a laminate member in the form of
a continuous strip of a laminate of a metal foil and a film
substrate. Polyester, polyethylene and the like may be mentioned as
the film substrate 110 which requires the use of an adhesive or the
like in the lamination treatment. On the other hand, ethylene-vinyl
acetate resin, ethylene-acrylic acid resin, ethylene-ethyl acrylate
resin, and ionomer resin may be mentioned as the film substrate 110
which does not always require the use of an adhesive in the
lamination treatment.
In the step (1), the lamination member formation treatment may be
carried out by coating a resin onto one side of a continuous metal
foil strip by a coating method such as extrusion coating or hot
melt coating.
Resins usable in the extrusion coating include polyolefins and
polyesters.
Resins usable in the hot melt coating include resins composed
mainly of ethylene-vinyl acetate resin, resins composed mainly of
polyesters, and resins composed mainly of polyamides.
The masking treatment in the step (2) is preferably carried out by
coating a resist onto the surface of a metal foil, drying the
coating, then subjecting the resist to contact exposure using a
predetermined pattern plate, performing development treatment to
form a predetermined resist pattern on the surface of the metal
foil, and optionally baking the resist pattern.
When the etching treatment of the metal foil is carried out using a
ferric chloride solution as an etching solution, the etching
solution can be easily circulated and reutilized and this can
easily realize continuous etching treatment in a continuous through
line.
When the iron material is a Ni--Fe (nickel-iron) alloy such as an
Invar material (42% Ni--Fe alloy), the etching solution is
contaminated with nickel. Therefore, to cope with this, the etching
solution should be properly controlled.
In the above embodiment, a method may also be adopted wherein a
feature not imparted to the pressure-sensitive color layer is
stacked on a separate film and this laminate is then stacked. For
example, the step of lamination may be provided wherein, after the
lamination treatment wherein a silicone separator (a
silicone-treated, easily separable PET film) is laminated, an NIR
layer (a near-infrared absorption layer) film comprising an NIR
layer provided on one side of a film and an AR layer (an
antireflection layer) film comprising an AR layer provided on one
side of a film are laminated in that order onto the surface of the
transparent film substrate remote from the mesh. In the step of
lamination, the NIR layer film is laminated through an adhesive
layer onto the surface of the transparent film substrate remote
from the mesh, and the AR layer film is then laminated through an
adhesive layer onto the NIR layer film. At least one of the
adhesive and the pressure-sensitive adhesive contains an absorber
which can absorb specific wavelengths, i.e., the wavelengths of
visible light and/or near-infrared.
By virtue of the above construction, the production process of an
electromagnetic wave shielding member according to the present
invention can produce an electromagnetic wave shielding member
provided with a mesh consisting of a thin metal film, adapted for
use in an electromagnetic wave shielding plate, which
electromagnetic wave shielding member has a capability of absorbing
specific wavelengths, i.e., the wavelengths of visible light and/or
near-infrared and good visibility, has satisfactory quality, and
can be produced with good productivity.
This can realize the mass production of an electromagnetic wave
shielding plate for a display such as PDP, as shown in FIG. 4 or
the like, which has a capability of absorbing specific wavelengths,
i.e., the wavelengths of visible light and/or near-infrared and
good visibility, see-through properties, and electromagnetic wave
shielding properties, in a high productivity rate.
In another embodiment, the production process comprises the steps
of: (1) laminate member formation treatment wherein a continuous
chromated metal foil strip and a continuous film substrate strip
are put on top of each other through
an adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or
an adhesive comprising (a) a polyesterpolyurethanepolyol produced
by reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate,
to form a continuous laminate member strip; (2) masking treatment
wherein, while carrying the laminate member in a continuous or
intermittent manner, an etching-resistant resist mask, for etching
the metal foil in the laminate member to form a mesh or the like,
is successively formed in a continuous or intermittent manner along
the longitudinal direction of the metal foil so as to cover the
metal foil on its surface remote from the film substrate; (3)
etching treatment wherein the metal foil in its portions exposed
from openings of the resist mask is etched to form a mesh or the
like consisting of a thin metal film; and lamination treatment
wherein, after the etching treatment, a pressure-sensitive adhesive
layer or a flattening layer containing an absorber capable of
absorbing specific wavelengths, i.e., the wavelengths of visible
light and/or near-infrared is optionally provided on the surface of
the mesh consisting of a thin metal film, and a silicone separator
(a silicone-treated, easily separable PET film) is laminated.
According to this construction, as with the preparation of a shadow
mask, for a cathode-ray tube for color TV, from a continuous strip
of a steel product, masking treatment and etching treatment can be
carried out in a continuous through line.
When the laminate member formation treatment is lamination
treatment wherein a continuous metal foil strip is laminated onto
the surface of a continuous film substrate strip through
an adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or
an adhesive comprising (a) a polyesterpolyurethanepolyol produced
by reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate,
to form a laminate member in a continuous strip form of a laminate
of the metal foil and the film substrate, the operation is simple
and the metal foil can be continuously etched with good
productivity. In particular, when the masking treatment is carried
out by coating a resist on the surface of a metal foil, drying the
coating, then subjecting the resist to contact exposure using a
predetermined pattern plate, performing development treatment to
form a predetermined resist pattern on the surface of the metal
foil, and optionally baking the resist pattern, advantages can be
offered including the realization of high-definition plate making
using a resist, satisfactory quality, and mass production.
In the present invention, prior to the laminate member formation
treatment, when both sides or one side of a copper foil or a metal
foil consisting of an iron material or the like are blackened by
chromate treatment, the reflection of light from the blackened
surface of the metal foil can be prevented. Before the chromate
treatment, preferably, copper bosses are deposited on the copper
foil.
In particular, before the laminate member formation treatment, when
both sides or one side of the metal foil are blackened by chromate
treatment, the need to perform blackening treatment by chromate
treatment in a later state can be eliminated and, consequently, the
working efficiency can be improved.
When both sides or one side of the copper foil or the metal foil
consisting of an iron material are not previously blackened by
chromate treatment, a method is used wherein, after the etching
treatment, the resist pattern is separated and removed and, if
necessary, washing treatment is carried out, followed by blackening
of the exposed surface of the mesh consisting of the thin metal
film by chromate treatment. In this case, however, the working
efficiency is poor.
More preferably, not only the viewer side but also the display side
is chromated because the stray of light from the display can be
prevented.
The chromate treatment refers to coating of a chromating liquid
onto a material to be treated. The chromating liquid may be coated,
for example, by roll coating, air curtain coating, electrostatic
spray coating, squeeze roll coating, or dip coating. In this case,
the coating is dried without washing with water.
In the present invention, the material to be treated is a mesh
consisting of the above-described metal foil or thin metal film. An
aqueous solution containing 3 g/liter of CrO.sub.2 is generally
used as the chromating liquid. "A chromating liquid prepared by
adding, to an aqueous chromic anhydride solution, a different
oxycarboxylic acid compound to reduce a part of chromium(VI) to
chromium(III)" may also be used. Specific examples of chromate
treatment methods include a method wherein one side or the whole of
the metal foil is dipped in an aqueous solution (25.degree. C.)
containing 3 g/liter of CrO.sub.2 for 3 sec, and a method which
comprises the steps of: adding, to an aqueous chromic anhydride
solution, a different oxycarboxylic acid compound to reduce a part
of chromium(VI) to chromium(III); roll coating the resultant
chromating liquid onto a metal foil; and drying the coating at
120.degree. C.
Oxycarboxylic acid compounds include tartaric acid, malonic acid,
citric acid, lactic acid, glucolic acid, glyceric acid, tropic
acid, benzilic acid, and hydroxyvaleric acid. These reducing agents
may be used alone or in a combination of two or more. The reduction
capability varies depending upon compounds. Therefore, the amount
of the reducing agent added is determined by grasping a reduction
to chromium(III). When the transparent film substrate is a PET film
(polyethylene terephthalate film), each treatment can be
successfully carried out without causing chemical attack.
The provision of the step of laminating, after the lamination of
the silicone separator (silicone-treated, easily separable PET
film), an NIR layer (a near-infrared absorption layer) film
comprising an NIR layer provided on one side of a film and an AR
layer (an antireflection layer) film comprising an AR layer
provided on one side of a film in that order onto the surface of
the transparent film substrate remote from the mesh, can realize
the preparation of an electromagnetic wave shielding member (a
front protection plate for displays) which has electromagnetic wave
shielding function and, in addition, near-infrared absorption
function and antireflection function. Further electromagnetic wave
shielding members (front protection plates for displays) include
those having a layer construction shown in FIGS. 7 and 8.
As shown in FIGS. 3C and 3D, when the pressure-sensitive adhesive
layer 135 or adhesive layer in the opening of the mesh consisting
of a thin metal film functions as a flattening layer, no problem
occurs. In general, however, as shown in FIG. 2G, the concaves and
convexes in the surface of the thin metal film (foil) provides a
rough surface which deteriorates transparency. Further, the
concaves and convexes in the mesh consisting of the thin metal film
makes it difficult to laminate the assembly onto a front panel of
glass or the like, an antireflection layer, a display or the like.
To overcome this drawback, preferably, before the formation of the
pressure-sensitive adhesive layer or the adhesive layer, a resin is
coated onto the assembly in its side of the mesh consisting of the
thin metal film to form a flattening resin layer 6 (see FIGS. 7 to
9). In coating the resin, care should be taken so as not to leave
air bubbles at the corner of the mesh consisting of the thin metal
film and to deteriorate the transparency. Preferred coating methods
for avoiding this unfavorable phenomenon include a method wherein a
coating material having low viscosity using a solvent or the like
is coated and the coating is then dried, and a method wherein a
resin is laminated while removing air.
Preferred resins usable for the flattening include those which have
high transparency and good adhesion to a dry lamination adhesive
and a copper mesh, and, when the flattening resin layer contains an
absorber capable of absorbing specific wavelengths, i.e., the
wavelengths of visible light and/or near-infrared, further has
excellent dispersion in each dispersant. The surface of the
flattening resin layer is particularly important from the viewpoint
of preventing moire and uneven interference in displays, and
minimizing protrusions, dents, lack of uniformity and the like is
preferred. For example, a resin layer having a high level of
flatness can be formed by coating or applying a resin, laminating a
substrate or the like having a high level of flatness onto the
coating, then exposing the coating to heat or light to cure the
resin, and separating the substrate. The resin is not particularly
limited so far as the above property requirements are satisfied.
However, acrylic ultraviolet-curable resins are preferred from the
viewpoints of coatability, hardcoat properties, easiness in
flattening and the like. Imparting pressure-sensitive adhesive
properties or adhesive properties to the resin can realize the
formation of a pressure-sensitive adhesive layer or an adhesive
layer having a high level of flatness which can reduce the number
of layers or the number of production steps.
In this embodiment, the metal foil 120 is a copper foil or an iron
material (a low-carbon steel substantially free from nickel), and,
before lamination, blackening treatment is carried out by chromate
treatment (S115 or S121) to blacken both sides of the metal foil
and, consequently, to form a chromate layer 122 (see FIG. 6B and
FIG. 1).
Here the chromation before the lamination means that a continuous
metal foil generally wound into a roll is supplied (S120) and is
previously chromated offline (S115). When the continuous metal
foil, which is supplied in a roll wound form (S120), is not
previously chromated offline (S115), a method may be used wherein,
in the step before the step of lamination, the metal foil is
chromated inline (S121).
The blackening treatment was carried out by chromate treatment. In
this case, a method was used wherein the metal foil 120 was dipped
in an aqueous solution (25.degree. C.) containing 3 g/liter of
CrO.sub.2 for 3 sec.
The film substrate 110 is not particularly limited so far as the
film substrate is highly transparent, can withstand the treatment,
and is highly stable. In general, however, a PET film is used. A
biaxially stretched PET film has good transparency, chemical
resistance, and heat resistance and thus is particularly
preferred.
As described above, polyester, polyethylene and the like may be
mentioned as the film substrate 110 which requires the use of an
adhesive or a pressure-sensitive adhesive in the step of lamination
treatment (S130). On the other hand, ethylene-vinyl acetate resin,
ethylene-acrylic acid resin, ethylene-ethyl acrylate resin, and
ionomer resin may be mentioned as the film substrate 110 which does
not always require the use of an adhesive in the step of lamination
treatment (S130).
In the present invention, an adhesive, comprising a styrene-maleic
acid copolymer-modified polyesterpolyurethane and an aliphatic
polyisocyanate, which is not stained by or deteriorated by the
etching solution, is used as the adhesive provided between the
transparent film substrate and the mesh consisting of a thin metal
film.
In another embodiment, the adhesive comprises (a) a
polyesterpolyurethanepolyol produced by reacting a polyesterpolyol
with a polyisocyanate, (b) a carboxyl-containing polyesterpolyol
produced by reacting a polyesterpolyol with an aromatic
polycarboxylic anhydride, and (c) a mixture of a trimethylolpropane
adduct of isophorone diisocyanate with a trimethylolpropane adduct
of xylylene diisocyanate. Examples of preferred adhesives usable
other than the above adhesives include adhesives of acrylic resins,
polyester resin, polyurethane resin, polyvinyl alcohol or partially
saponified product of polyvinyl alcohol (tradename: Poval), vinyl
chloride-vinyl acetate copolymer, ethylene-vinyl acetate copolymer,
and, from the viewpoints of no significant dyeing with and
deterioration by the etching solution, post treatment, lamination,
coatability and the like, heat-curable resins and
ultraviolet-curable resins.
Polyester resins are also preferred particularly from the
viewpoints of adhesion to transparent polymeric substrates,
compatibility with and dispersion in the above-described visible
light absorbers and infrared absorbers (hereinafter referred to
also as "near-infrared absorbers") and the like.
In order to impart the capability of absorbing visible light and/or
near-infrared, an absorber (a visible light absorber or a
near-infrared absorber), which can absorb specific wavelengths,
i.e., the wavelengths of visible light and/or near-infrared, is
optionally mixed and dispersed in the adhesive.
The adhesive layer may be coated to a thickness of 1 to 100 .mu.m
onto a film substrate by various coating methods such as roll
coating, Mayer bar coating, or gravure coating.
Pressure-sensitive adhesives include, for example, natural rubber,
synthetic rubber, acrylic resin, polyvinyl ether, urethane resin,
and silicone resin pressure-sensitive adhesives. Specific examples
of synthetic rubber pressure-sensitive adhesives include
styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber
(NBR), polyisobutylene rubber, isobutylene-isoprene rubber,
isoprene rubber, styrene-isoprene block copolymer,
styrene-butadiene block copolymer, and styene-ethylene-butylene
block copolymer.
Specific examples of silicone resin pressure-sensitive adhesives
include dimethylpolysiloxane. These pressure-sensitive adhesives
may be used alone or in a combination of two or more.
In order to impart the capability of absorbing visible light and/or
near-infrared, an absorber (a visible light absorber or a
near-infrared absorber), which can absorb specific wavelengths,
i.e., the wavelengths of visible light and/or near-infrared, is
optionally mixed and dispersed in the pressure-sensitive adhesive.
Further, if necessary, tackifiers, fillers, softeners,
antioxidants, ultraviolet absorbers, crosslinking agents and the
like are mixed and dispersed in the pressure-sensitive
adhesive.
The pressure-sensitive adhesive layer may be formed to a thickness
of 1 to 100 .mu.m, preferably 10 to 50 .mu.m, onto a film substrate
by various coating methods such as roll coating, Mayer bar coating,
or gravure coating. Next, masking treatment (S150) and etching
treatment (S160) are carried out. In the masking treatment (S150),
while carrying the laminate member 190 in a continuous or
intermittent manner, in such a state that the laminate member 190
is stretched without loosening, an etching-resistant resist mask,
for etching the metal foil in the laminate member to form a mesh or
the like, is successively formed in a continuous or intermittent
manner along the longitudinal direction of the metal foil. In the
etching treatment (S160), the metal foil in its portions exposed
from the resist mask is etched to form a mesh or the like
consisting of a thin metal film.
As shown in FIG. 3A, etched portions 120C of a mesh or the like are
provided at predetermined intervals in the metal foil in the
longitudinal direction of the laminate member 190. In this
embodiment, the etched portions 120C are comprised of a mesh
portion 120A and a grounding frame portion 120B as shown in FIG.
3B. The mesh portion 120A is a electromagnetic wave shielding
region.
An example of the masking treatment comprises a series of
treatments, that is, the steps of: coating a photosensitive resist,
such as casein or PVA, onto a metal foil 120 (S151); drying the
coating (S152); then subjecting the coating to contact exposure
using a predetermined pattern plate (S153); developing the exposed
coating with water (S154); performing hardening treatment and the
like; and baking the resist pattern (S155).
The coating of a resist is generally carried out by coating a
resist, such as water-soluble casein, PVA, or gelatin, onto both
sides or one side (metal foil side) of the laminate member by
dipping, curtain coating, or flow coating while carrying the
laminate member. In the case of the casein resist, baking at a
temperature of about 200 to 300.degree. C. is preferred. In order
to prevent the warpage or curling of the laminate member 190,
however, if possible, curing is carried out at a lowest possible
temperature. When the dry film resist is a photosensitive resist,
the working efficiency of the step of resist coating (S151) is
good.
According to a preferred embodiment of the present invention, in
the etching treatment, a ferric chloride solution is used as the
etching solution. In this case, the etching solution can be easily
circulated and reutilized, and the etching treatment can be easily
carried out in a continuous manner. In this embodiment, the masking
treatment (S150) and the etching treatment (S160) are carried out
in such a state that the laminate member 190 is stretched without
loosening. The masking treatment (S150) and the etching treatment
(S160) are carried out in fundamentally the same manner as used in
the preparation of a shadow mask for cathode-ray tubes for color
TV, from a continuous steel product strip, particularly in the
etching treatment from one side of a thin sheet (20 .mu.m to 80
.mu.m). That is, the masking treatment and the etching treatment
can be carried out in a continuous through line, and the metal foil
in a continuous laminate member strip formed of a laminate of the
metal foil and the film can be continuously etched with good
productivity.
After the etching treatment (S160), washing treatment and the like
are carried out, a pressure-sensitive adhesive layer (corresponding
to 135 in FIG. 3) serving also as a flattening layer is provided on
the surface of the metal foil in a mesh form, and a silicone
separator (a silicone-treated, easily separable PET film) is then
laminated (S180). The pressure-sensitive adhesive for the formation
of the pressure-sensitive adhesive layer may be the same as the
above-described pressure-sensitive adhesive. The provision of the
pressure-sensitive adhesive layer may be carried out by roll
coating, die coating, blade coating, screen printing or the like.
When the electromagnetic wave shielding member is used in an
electromagnetic wave shielding plate, the silicone separator is
separated from the pressure-sensitive adhesive layer, that is, is a
temporary protective film. Thus, an electromagnetic wave shielding
member having a layer construction shown in FIG. 3C is
prepared.
Next, an NIR layer film 150 is laminated through an adhesive layer
(S190), and an AR layer film 160 is then laminated onto the NIR
layer film 150 through an adhesive layer (S200). The adhesive for
each of the adhesive layers may be the above adhesive. For example,
highly transparent acrylic or other adhesives may be used. For
example, a pressure-sensitive adhesive (stock No. PSA-4,
manufactured by Lintec Corporation) may be mentioned as a
commercially available adhesive.
The NIR layer film (150 in FIG. 3D) is a film comprising an NIR
layer (a near-infrared absorption layer) provided on a transparent
film. No. 2832 manufactured by Toyobo Co., Ltd., comprising an NIR
layer coated onto a polyethylene terephthalate (PET) film, is a
generally known commercially available NIR layer film.
Near-infrared generally refers to a region of 780 nm to 1000 nm,
and the absorption in this wavelength region is preferably not less
than 80%. Absorbers (absorbing agents) capable of absorbing
specific wavelengths, i.e., the wavelengths of near-infrared
include: inorganic infrared absorbers, such as tin oxide, indium
oxide, magnesium oxide, titanium oxide, chromium oxide, zirconium
oxide, nickel oxide, aluminum oxide, zinc oxide, iron oxide,
antimony oxide, lead oxide, and bismuth oxide; and organic infrared
absorbers such as cyanine compounds, phthalocyanine compounds,
naphthalocyanine compounds, naphthoquinone compounds, anthraquinone
compounds, diimoniums, nickel complexes, and dithiol complexes. The
inorganic infrared absorber is preferably in the form of fine
particles which preferably have an average particle diameter in the
range of 0.005 to 1 .mu.m, particularly preferably in the range of
0.01 to 0.5 .mu.m. In order to improve visible light transmittance,
preferably, the fine particles of the inorganic infrared absorber
have a particle size distribution such that the diameter of the
fine particles is not more than 1 .mu.m. Preferably, the infrared
absorber is dispersed on a high dispersion level. Metals and
pigments, which will be described later, may be mentioned as the
absorber (absorbing agent) capable of absorbing visible light.
The absorption layer for visible light region (380 to 780 nm) is
provided for obtaining a color balance of displays or for absorbing
external light to improve the contrast. The light transmittance of
the visible light absorption layer is preferably in the range of 50
to 98%.
Metals as the absorber capable of absorbing wavelengths of visible
light include, for example, Nd (neodymium), Au (gold), Pt
(platinum), Pd (palladium), Ni (nickel), Cr (chromium), Al
(aluminum), Ag (silver), In.sub.2O.sub.3--SnO.sub.2, CuI, CuS, and
Cu (copper). They may be used solely or in a combination of two or
more. A visible light absorption layer may be formed, for example,
by vapor deposition, CVD, or sputtering. Conventional pigments may
be mentioned as the pigment used as the visible light absorber.
Specific examples of such pigments include phthalocyanine, azo,
condensed azo, azolake, anthraquinone, perylene or perinone, indigo
or thioindigo, isoindolino, azomethineazo, dioxyzane, quinacridone,
aniline black, triphenylmethane, or other organic pigments, and
carbon black, neodymium compound, titanium oxide, iron oxide, iron
hydroxide, chromium oxide, spinel-type sinter, chromic acid, chrome
vermilion, iron blue, aluminum powder, bronze powder or other
pigments.
Although the NIR layer (near-infrared absorption layer) is not
particularly limited, the NIR layer preferably has steep absorption
in the near-infrared region, has high light transmittance in the
visible region, and does not have any large absorption of specific
wavelengths, i.e., wavelengths in the visible region.
For example, a layer comprising at least one coloring matter,
having a maximum absorption wavelength between light wavelength 800
nm and light wavelength 1000 nm, dissolved in a binder resin may be
used as the NIR layer (near-infrared absorption layer), and the
thickness of the NIR layer is about 1 to 50 .mu.m.
Examples of the coloring matter include cyanine compounds,
phthalocyanine compounds, naphthalocyanine compounds,
naphthoquinone compounds, anthraquinone compounds, and dithiol
complexes.
Binder resins include polyester resins, polyurethane resins, and
acrylic resins. Crosslinked and cured binders using a reaction of
epoxy, acrylate, methacrylate, isocyanate group or the like by
ultraviolet irradiation or by heating may also be used. Solvents
usable for coating include cyclic ethers or ketones capable of
dissolving the above coloring matter, for example, tetrahydrofuran,
dioxane, cyclohexane, and cyclopentanone.
The AR layer film generally has a layer construction as indicated
by 160 in FIG. 3D and is a film comprising an AR layer provided on
a transparent film.
The AR layer (antireflection layer) functions to prevent the
reflection of visible light. Various AR layers having a
single-layer or multilayer structure are known. AR layers having a
multilayer structure are generally such that high-refractive index
layers and low-refractive index layers are alternately stacked. The
material for the antireflection layer is not particularly limited.
The antireflection layer may be formed by a dry method, such as
sputtering or vapor deposition, or by wet coating. The
high-refractive index layer is formed of niobium oxide, titanium
oxide, zirconium oxide, ITO or the like. The low-refractive index
layer is generally formed of silicon oxide.
The hardcoat 162 in the AR layer film (corresponding to 160 in FIG.
3D) may be formed by heat- or ionizing radiation-curing a
polyfunctional acrylate, for example, a polyester acrylate, such as
DPHA, TMPTA, or PETA, urethane acrylate, or epoxy acrylate. Here
"having hard properties" or "hardcoat" refers to a hardness of H or
more as measured by a pencil hardness test specified in JIS K
5400.
The antifouling layer 164 stacked onto the AR layer (163 in FIG.
3D) is a water-repellent, oil-repellent coating, and examples
thereof include siloxane anifouling coatings and fluoro antifouling
coatings such as fluorinated alkylsilyl compound antifouling
coatings.
The AR layer is laminated, and, in such a state that the assembly
is stretched without loosening, the assembly is cut (S210) at
predetermined positions into each electromagnetic wave shielding
member having a layer construction shown in FIG. 3D (S220).
For example, the electromagnetic wave shielding member having a
layer construction shown in FIG. 3D thus obtained may be applied to
one side of a transparent substrate, such as a glass substrate,
followed by the application of an AR layer film (corresponding to
160 in FIG. 3D) to the other side of the transparent substrate to
prepare an electromagnetic wave shielding plate. Glass, polyacrylic
resin, and polycarbonate resin substrates are suitable as the
transparent substrate. If necessary, other plastic films may be
used.
Plastic films usable herein include triacetylcellulose films,
diacetylcellulose films, acetate butyrate cellulose films,
polyether sulfone films, polyacrylic resin films, polyurethane
resin films, polyester films, polycarbonate films, polysulfone
films, polyether films, trimethylpentene films, polyether ketone
films, and (meth)acrylonitrile films. Biaxially stretched
polyesters are particularly preferred because of their excellent
transparency and durability. In general, the thickness thereof is
preferably about 8 to 1000 .mu.m.
For large displays, a 1 to 10 mm-thick rigid substrate is used. On
the other hand, for small displays for a character display tube, a
0.01 to 0.5 mm-thick plastic film having suitable flexibility is
applied to the display.
The light transmittance of the transparent substrate is ideally
100%. The selection of a transparent substrate having a light
transmittance of not less than 80% is preferred.
In a variant of the above embodiment, instead of S180, a flattening
resin layer 6 is provided on the metal mesh portion 5 in its
concave/convex face. An antireflection layer or an antiglare layer
may be stacked onto the flattening resin layer 6, 13 (FIGS. 7 and
8). In another variant of the above embodiment, instead of S180, a
flattening resin layer 6 is provided on the metal mesh portion 5 in
its concave/convex face, and an adhesive layer containing an
absorber (a visible light absorber, near-infrared absorber) is
laminated onto the flattening resin layer 6 (FIG. 9). A further
variant of the above embodiment is such that, prior to the laminate
treatment S130 in this embodiment, blackening treatment is not
carried out on at least one side of the metal foil 120, the steps
up to the etching treatment (S160) are carried out in the same
manner as in this embodiment, the surface portion of the metal foil
120 is then blackened by chromate treatment as blackening
treatment, and, thereafter, in the same manner as in this
embodiment, the lamination treatment for laminating a silicone
separator (a silicone-treated, easily separable PET film) and steps
after the lamination treatment are carried out. Further, if
necessary, a method may also be adopted wherein, before cutting
(S210), the assembly is wound into a roll and the treatment is
temporarily stopped. If necessary, the step of slitting the
laminate member 190 into a predetermined width may be provided
before the masking treatment (S190). In this embodiment, a copper
foil is used as the metal foil. An iron material or the like may be
used as the metal foil. In still another variant, after the
lamination of the NIR layer film (S190), if necessary, a protective
film is applied, followed by cutting to prepare an electromagnetic
wave shielding member.
Next, a second embodiment of the production process of an
electromagnetic wave shielding member according to the present
invention will be described with reference to FIG. 1.
The second embodiment is different from the first embodiment in the
laminate member formation treatment. In the laminate member
formation treatment in the second embodiment, a resin is coated
(S135) onto one side of a continuous metal foil strip by a coating
method such as extrusion coating or hot melt coating to prepare a
laminate member (S140).
As described above, extrusion coating materials include polyolefins
and polyesters, and hot melt coating materials include resins
composed mainly of ethylene-vinyl acetate resin, resins composed
mainly of polyesters, and resins composed mainly of polyamides.
In the second embodiment, since the construction except for the
laminate member formation treatment is the same as the construction
of the first embodiment, the overlapped explanation will be
omitted.
Next, a third embodiment of the production process of an
electromagnetic wave shielding member according to the present
invention will be described with reference to FIG. 1.
In this embodiment, as with the first embodiment, a member for the
production of an electromagnetic wave shielding plate which, in
use, is placed in front of a display such as PDP shown in FIG. 5.
Specifically, in this embodiment, there is provided a process for
mass-producing an electromagnetic wave shielding member having
electromagnetic wave shielding properties and see-through
properties and comprising a transparent film substrate and a mesh
consisting of a thin metal film at least one surface of which has
been blackened by chromate treatment, said mesh being laminated on
one side of the substrate through
an adhesive comprising a styrene-maleic acid copolymer-modified
polyesterpolyurethane and an aliphatic polyisocyanate, or
an adhesive comprising (a) a polyesterpolyurethanepolyol produced
by reacting a polyesterpolyol with a polyisocyanate, (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol with an aromatic polycarboxylic anhydride, and (c)
a mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate,
wherein
a 1 to 100 .mu.m-thick copper foil or iron material (low-carbon
steel), at least one surface of which has been blackened by
chromate treatment, is used as a metal foil for the formation of
the mesh consisting of a thin metal film.
In this embodiment, steps up to the lamination treatment (S180) for
laminating a silicone separator (a silicone-treated, easily
separable PET film) are carried out in the same manner as in the
first embodiment. Thereafter, the assembly is cut (S185) into each
electromagnetic wave shielding member preparation region in a sheet
form. An NIR layer film and an AR layer film each in a sheet form
corresponding to the electromagnetic wave shielding member
preparation region are successively laminated through an adhesive
layer (S195, S205) to prepare an electromagnetic wave shielding
member (S220).
Since the material for each portion and the treatment method are
the same as those in the first embodiment, the explanation thereof
will be omitted. In this embodiment, a method may also be adopted
wherein the cut electromagnetic wave shielding member preparation
region (S185) having a layer construction corresponding to FIG. 3C)
as such may be provided as an electromagnetic wave shielding member
and this electromagnetic wave shielding member, either alone or in
combination with an AR layer film and an NIR layer film, is applied
to a transparent substrate, such as a glass substrate, to prepare
an electromagnetic wave shielding plate.
The cross section of a characteristic portion in each treatment
(cross section at position P1-P2 in FIG. 3B) up to the lamination
treatment (S180) in the first and third embodiments will be further
briefly described with reference to FIG. 2.
FIGS. 2A to 2G are cross-sectional views taken on position P1 P2 of
FIG. 3B. Specifically, FIGS. 2A to 2G show an embodiment wherein an
adhesive is used in the laminate treatment (S130) for laminating a
PET film or the like. A metal foil 120 (FIG. 2B) is provided on one
side of a film substrate 110 (FIG. 2A) through an adhesive layer
130 by the lamination treatment (S130 in FIG. 1). A photosensitive
resist is coated onto the metal foil 120, and the coating is dried
(FIG. 2C). Thereafter, contact exposure is carried out using a
predetermined pattern plate, and the exposed coating is developed
and is baked to form a predetermined resist pattern 180 as shown in
FIG. 2D.
Next, the metal foil 120 is etched from one side thereof (FIG. 2E)
using the resist pattern 180 as an etching-resistant mask. After
washing treatment and the like, a pressure-sensitive adhesive layer
135 is provided on the surface of the metal foil 120, and a
silicone separator 140 is laminated through the pressure-sensitive
adhesive layer 135 (FIG. 2G).
EXAMPLES
The following examples further illustrate the present
invention.
Example 1
In the following example, a part of a production process of an
electromagnetic wave shielding member as a first example of the
embodiment shown in FIG. 1 was carried out.
In the first example of the embodiment shown in FIG. 1, the
following adhesive 1 was roll coated on one side of a polyethylene
terephthalate (hereinafter referred to also as "PET") film having a
thickness of 188 .mu.m and a width of 700 mm as a film substrate (A
4300, manufactured by Toyobo Co., Ltd.), and the coating was dried
to form an adhesive layer at a coverage of 4 g/m.sup.2.
Adhesive 1:
An ethyl acetate solution (100 parts by weight) of a styrene-maleic
acid copolymer-modified polyesterpolyurethane (solid content
(hereinafter referred to also as "NV") 50%, manufactured by ROCK
PAINT CO., LTD.) was mixed with 10 parts by weight of an ethyl
acetate solution of an aliphatic polyisocyanate (NV 75%,
manufactured by ROCK PAINT CO., LTD.) to prepare a mixed solution.
This mixed solution (100 parts by weight) was mixed with 45 parts
by weight of ethyl acetate to prepare an adhesive 1.
A copper foil (EXP-WS, width 700 mm, thickness 9 .mu.m,
manufactured by Furukawa Circuit Foil Co., Ltd.), wherein both
sides of a copper layer 1200 with copper bosses 1300 deposited on
its one side had been blackened by chromate treatment, as shown in
FIG. 12 was provided as a metal foil.
The copper foil 1200 and the PET film were laminated on top of each
other by means of a laminator comprising a metallic roll and a
rubber roll so that the chromate layer 1100 (blackening layer) of
the copper foil 1200 on its side, where the copper bosses 1300 had
been deposited, faced the adhesive layer side of the PET film, with
caution so as not to cause cockling or to form air bubbles. Thus, a
laminate member 190 (sheet) having a total thickness of 200 .mu.m
was prepared.
A process from masking to etching was then performed by a
continuous through line, that is, a shadow mask line (hereinafter
referred to also as "SM line"). In this SM line, a shadow mask for
a cathode-ray tube for color TV is prepared from a strip-shaped
continuous steel product (thin plate; 20 .mu.m to 80 .mu.m) by a
process for masking and etching from one side of the steel product
in such a state that the steel product is stretched.
Casein was provided as a photosensitive resist and was flow coated
so as to cover the whole one side (metal foil side) of the laminate
member 190 while carrying the laminate member 190.
A pattern plate for forming a mesh portion 120A and a grounding
frame portion 120B as shown in FIG. 3B was provided which had a
mesh angle of 30 degrees, a mesh line width of 20 .mu.m, and a mesh
pitch (corresponding to Px and Py in FIG. 4) of 200 .mu.m. This was
used to carry out contact exposure with a printing frame in the SM
line (S153), and the exposed coating was then developed with water
(S154), was subjected to hardening treatment and the like, and was
further baked at 100.degree. C. (S155).
Next, in such a state that the laminate member 190 was stretched, a
ferric chloride solution of 42 Baume degrees at 50.degree. C. as an
etching solution was sprayed on the metal foil using the resist
pattern as an etching-resistant mask to etch the exposed region,
whereby a mesh portion and a grounding frame portion were
formed.
Next, in the SM line, in such a state that the laminate member 190
was stretched, the laminate member 190 was washed with water, the
resist was separated with an alkaline solution, and, further,
washing, drying and the like were carried out. Thus, a test film 1
was prepared.
Comparative Example 1
A test film 2 was prepared in the same manner as in Example 1,
except that the adhesive 1 was changed to the following adhesive
2.
Adhesive 2:
An ethyl acetate solution (100 parts by weight) of a styrene-maleic
acid copolymer-modified polyesterpolyurethane (solid content (NV)
50%, manufactured by ROCK PAINT CO., LTD.) was mixed with 10 parts
by weight of an ethyl acetate solution of an aromatic
polyisocyanate (solid content (NV) 75%, manufactured by ROCK PAINT
CO., LTD.) to prepare a mixed solution. This mixed solution (100
parts by weight) was mixed with 45 parts by weight of ethyl acetate
to prepare an adhesive 2.
Comparative Example 2
A test film 3 was prepared in the same manner as in Example 1,
except that the adhesive 1 was changed to the following adhesive
3.
Adhesive 3:
An ethyl acetate solution (100 parts by weight) of
polyesterpolyurethane (solid content (NV) 50%, manufactured by
Takeda Chemical Industries, Ltd.) was mixed with 10 parts by weight
of an ethyl acetate solution of an aliphatic polyisocyanate (solid
content (NV) 75%, manufactured by Takeda Chemical Industries, Ltd.)
to prepare a mixed solution. This mixed solution (100 parts by
weight) was mixed with 45 parts by weight of ethyl acetate to
prepare an adhesive 3.
Example 2
In the following example, a part of a production process of an
electromagnetic wave shielding member as a first example of the
embodiment shown in FIG. 1 was carried out.
In the first example of the embodiment shown in FIG. 1, the
following adhesive 4 was roll coated on one side of a polyethylene
terephthalate (hereinafter referred to also as "PET") film having a
thickness of 0.1 mm and a width of 700 mm as a film substrate (A
4300, manufactured by Toyobo Co., Ltd.), and the coating was dried
to form an adhesive layer at a coverage of 4 g/m.sup.2.
Adhesive 4:
An ethyl acetate solution (100 parts by weight) of a resin produced
by mixing (a) a polyesterpolyurethanepolyol, produced by reacting
isophorone diisocyanate with a mixture of a polyesterpolyol,
produced by esterifying isophthalic acid with ethylene glycol and
neopentyl glycol, with a polyesterpolyol produced by esterifying
isophthalic acid with diethylene glycol, with (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol, produced by esterifying isophthalic acid with
ethylene glycol, neopentyl glycol, and 2,5-hexanediol, with
trimellitic anhydride (this ethyl acetate solution of the resin
being manufactured by Takeda Chemical Industries, Ltd.; NV 50%) was
mixed with (c) 10 parts by weight of an ethyl acetate solution of a
mixture of a trimethylolpropane adduct of isophorone diisocyanate
with a trimethylolpropane adduct of xylylene diisocyanate (this
ethyl acetate solution of the mixture being manufactured by Takeda
Chemical Industries, Ltd.; NV 75%).
This mixed solution (100 parts by weight) was mixed with 45 parts
by weight of ethyl acetate to prepare an adhesive 4.
A copper foil (electrolytic copper foil manufactured by Furukawa
Circuit Foil Co., Ltd.; B-WS, width 700 mm, thickness 0.01 mm,),
wherein both sides of a copper layer 1200 with copper bosses 1300
deposited on its one side had been blackened by chromate treatment,
as shown in FIG. 12 was provided as a metal foil.
The copper foil 1200 and the PET film were laminated on top of each
other by means of a laminator comprising a metallic roll and a
rubber roll so that the chromate layer 1100 (blackening layer) of
the copper foil 1200 on its side, where the copper bosses 1300 had
been deposited, faced the adhesive layer side of the PET film, with
caution so as not to cause cockling or to form air bubbles. Thus, a
laminate member 190 (sheet) having a total thickness of 200 .mu.m
was prepared.
A process from masking to etching was then performed by a
continuous through line, that is, a shadow mask line (hereinafter
referred to also as "SM line"). In this SM line, a shadow mask for
a cathode-ray tube for color TV is prepared from a strip-shaped
continuous steel product (thin plate; 20 .mu.m to 80 .mu.m) by a
process for masking and etching from one side of the steel product
in such a state that the steel product is stretched.
Casein was provided as a photosensitive resist and was flow coated
so as to cover the whole one side (metal foil side) of the laminate
member 190 while carrying the laminate member 190.
A pattern plate for forming a mesh portion 120A and a grounding
frame portion 120B as shown in FIG. 3B was provided which had a
mesh angle of 30 degrees, a mesh line width of 20 .mu.m, and a mesh
pitch (corresponding to Px and Py in FIG. 4) of 200 .mu.m. This was
used to carry out contact exposure with a printing frame in the SM
line (S153), and the exposed coating was then developed with water
(S154), was subjected to hardening treatment and the like, and was
further baked at 100.degree. C. (S155).
Next, in such a state that the laminate member 190 was stretched, a
ferric chloride solution of 42 Baume degrees at 50.degree. C. as an
etching solution was sprayed on the metal foil using the resist
pattern as an etching-resistant mask to etch the exposed region,
whereby a mesh portion and a grounding frame portion were
formed.
Next, in the SM line, in such a state that the laminate member 190
was stretched, the laminate member 190 was washed with water, the
resist was separated with an alkaline solution, and, further,
washing, drying and the like were carried out. Thus, a test film 4
was prepared.
Comparative Example 3
A test film 5 was prepared in the same manner as in Example 2,
except that the adhesive 4 was changed to the following adhesive
5.
Adhesive 5:
An ethyl acetate solution (100 parts by weight) of a resin produced
by mixing (a) a polyesterpolyurethanepolyol, produced by reacting
isophorone diisocyanate with a mixture of a polyesterpolyol,
produced by esterifying isophthalic acid with ethylene glycol and
neopentyl glycol, with a polyesterpolyol produced by esterifying
isophthalic acid with diethylene glycol, with (b) a
carboxyl-containing polyesterpolyol produced by reacting a
polyesterpolyol, produced by esterifying isophthalic acid with
ethylene glycol, neopentyl glycol, and 2,5-hexanediol, with
trimellitic anhydride (this ethyl acetate solution of the resin
being manufactured by Takeda Chemical Industries, Ltd.; NV 50%) was
mixed with (c) 10 parts by weight of an ethyl acetate solution of a
trimethylolpropane adduct of tolylene diisocyanate (this ethyl
acetate solution of the adduct being manufactured by Takeda
Chemical Industries, Ltd.; NV 75%).
This mixed solution (100 parts by weight) was mixed with 45 parts
by weight of ethyl acetate to prepare an adhesive 5.
Comparative Example 4
A test film 6 was prepared in the same manner as in Example 2,
except that the adhesive 4 was changed to the following adhesive
6.
Adhesive 6:
(a) A polyesterpolyurethanepolyol (100 parts by weight) produced by
reacting tolylene diisocyanate with a polyesterpolyol produced by
esterifying isophthalic acid with ethylene glycol and neopentyl
glycol (this polyesterpolyurethanepolyol being manufactured by
Takeda Chemical Industries, Ltd.; NV 50%) was mixed with (c) 10
parts by weight of an ethyl acetate solution of a
trimethylolpropane adduct of xylylene diisocyanate (this ethyl
acetate solution of the adduct being manufactured by Takeda
Chemical Industries, Ltd.; NV 75%).
This mixed solution (100 parts by weight) was mixed with 45 parts
by weight of ethyl acetate to prepare an adhesive 6.
The results of the measurement of optical characteristics of test
films 1 to 3 are shown in Table 1. Here .DELTA.AB* is represented
by equation (1):
.DELTA.AB*=(.DELTA.a*.times..DELTA.a*+.DELTA.b*.times..DELTA.b*).sup-
.1/2 (1)
TABLE-US-00001 TABLE 1 Sample No. .DELTA.a* .DELTA.b* .DELTA.a*
ratio .DELTA.b* ratio .DELTA.AB* Tt % Test film 1 -0.559 3.385
0.334868 0.598519 3.431029 88.7 (Ex. 1) Test film 2 -0.878 5.579
0.526202 0.986451 5.648039 88.1 (Comp. Ex. 1) Test film 3 -1.669
5.656 1 1 5.897015 87.3 (Comp. Ex. 2) Test film 4 -0.651 3.792
0.3333 0.5874 3.8475 85.3 (Ex. 2) Test film 5 -0.969 6.215 0.4962
0.9627 6.2901 85.1 (Comp. Ex. 3) Test film 6 -1.953 6.456 1 1
6.7449 87.3 (Comp. Ex. 4) Here .DELTA.a*, .DELTA.b*, .DELTA.a*
ratio, .DELTA.b* ratio, .DELTA.AB*, Tt [%] have the following
respective meanings. .DELTA.a*: Transmission chromaticity
difference of L*a*b* color system .DELTA.b*: Transmission
chromaticity difference of L*a*b* color system .DELTA.a* ratio:
.DELTA.a* ratio of each sample based on .DELTA.a* of test films 3
and 6 .DELTA.b* ratio: .DELTA.b* ratio of each sample based on
.DELTA.b* of test films 3 and 6 .DELTA.AB*: Chromaticity difference
obtained by combining chromaticity differences of .DELTA.a* and
.DELTA.b* Tt [%]: Total light transmittance
Measuring methods for each numerical value shown in Table 1 and
acceptable value range for properties (excellent etching
resistance, excellent optical characteristics, and color change)
will be described.
Etching resistance: Pattern remaining after etching is not
separated.
Optical characteristics: Conceptually, the light transmittance is
high, and the film is colorless.
In Table 1, since Tt (total light transmittance) is substantially
identical for test films 1 to 6, a .DELTA.AB* value of not more
than 4 and not less than 0 (zero) is regarded as acceptable.
From the results shown in Table 1 and the like, it is apparent that
electromagnetic wave shielding members bonded with
an adhesive comprising a mixture of a styrene-maleic acid
copolymer-modified polyesterpolyurethane with an organic
polyisocyanate, or
an adhesive comprising a mixture of (a) a
polyesterpolyurethanepolyol produced by reacting a polyesterpolyol
with a polyisocyanate with (b) a carboxyl-containing
polyesterpolyol produced by reacting a polyesterpolyol with an
aromatic polycarboxylic anhydride and (c) a mixture of a
trimethylolpropane adduct of isophorone diisocyanate with a
trimethylolpropane adduct of xylylene diisocyanate
are excellent in etching resistance, as well as in optical
characteristics. In particular, the electromagnetic wave shielding
member bonded with the adhesive comprising an aliphatic isocyanate
prepared in Example 1 and the electromagnetic wave shielding member
bonded with the adhesive comprising a mixture of a
trimethylolpropane adduct of isophorone diisocyanate with a
trimethylolpropane adduct of xylylene diisocyanate prepared in
Example 2 are free from a change in color of the adhesive upon
etching and are excellent in etching resistance, as well as in
optical characteristics.
Example 3
The test films 1 and 4 were subjected to the following flattening
treatment.
Flattening Treatment:
A urethane ultraviolet-curable resin having a viscosity of 1500
mPas was provided and was coated by screen printing to a thickness
of 40 .mu.m on only the concave-convex face of a metal foil (a mesh
portion) so as not to cover the ground electrode portion around the
test film 1.
Further, a 38 .mu.m-thick untreated PET film having high surface
smoothness was laminated as a peel film by means of a laminator
onto the screen printed face.
Thereafter, the print was cured with ultraviolet light at a dose of
200 mJ/cm.sup.2, and the 38 .mu.m-thick untreated PET film having
high surface smoothness was separated to produce a flattened
metallic mesh sheet.
TABLE-US-00002 Color adhesive layer: Color adhesive material:
Nickel complex compound 2 pts. wt. (near-infrared absorber)
Neodymium oxide 2 pts. wt. (visible light absorber) Polyester resin
550 pts. wt. Methyl ethyl ketone 920 pts. wt. Toluene 920 pts.
wt.
The color adhesive material was dispersed and mixed by means of a
triple roll to prepare a color adhesive. Next, the color adhesive
was coated by means of a 100 .mu.m applicator onto the surface of
the flattened layer in the flattened metallic mesh sheet. The
coating was then dried at about 90.degree. C. to remove the
solvent. Thus, an electromagnetic wave shielding member was
prepared which had a layer construction such that a 10 .mu.m-thick
color adhesive layer was formed. A glass plate was stacked onto the
electromagnetic wave shielding member in its color adhesive layer
side.
Measurement of Spectral Transmittance and Reflectance:
The reflectance and transmittance of visible light at wavelengths
of 380 to 780 nm were measured with a spectrometer UV-3100 PC
manufactured by Shimadzu Seisakusho Ltd., and the transmittance of
near-infrared at a wavelength of 1000 nm was measured with an
integrating sphere.
Results of Measurement of Spectral Transmittance and
Reflectance:
TABLE-US-00003 (i) For visible light at wavelengths of 380 to 780
nm, transmittance (T %) 62% reflectance (R %) 15% R/T 0.24 (ii) For
near-infrared at a wavelength of 1000 nm, transmittance (T %)
11%
Comparative Example 5
The procedure of Example 3 was repeated, except that the
ingredients of the color adhesive material were changed as
follows.
TABLE-US-00004 Color adhesive material: Polyester resin 550 pts.
wt. Methyl ethyl ketone 920 pts. wt. Toluene 920 pts. wt.
The spectral transmittance and reflectance of the electromagnetic
wave shielding member thus obtained were measured. The results are
shown below.
Results of Measurement of Spectral Transmittance and
Reflectance:
TABLE-US-00005 (i) For visible light at wavelengths of 380 to 780
nm, transmittance (T %) 77% reflectance (R %) 38% R/T 0.49 (ii) For
near-infrared at a wavelength of 1000 nm, transmittance (T %)
92%
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